1. Growth
Populations
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2. Geographic distribution – the area a pop lives(range)
How Populations Grow
Geographic distribution – the area a pop lives(range)

3. Population Density – the number of individuals in an area

4. Number of births Number of deaths Emigration (out) & Immigration (in)
Population Growth
Number of births
Number of deaths
Emigration (out) & Immigration (in)

5. In Springfield, 45 babies are born in the year 2008
In Springfield, 45 babies are born in the year people died that same year. What is the growth rate for the city?
Positive Growth rate = population increase Negative Growth rate = decrease

6. Exponential Growth –reproduce at a constant rate
Exponential Growth –reproduce at a constant rate. Occurs under ideal conditions (no limits)
J-shape curve

7. Limiting Factors
Limiting Factor – causes population growth to decrease
Limiting factors include: food, predators, disease, natural disasters. Etc.

8. Why does exponential growth occur?
Mice can breed about every 5 weeks or so. One litter of mice can produce mice.

9. Logistic Growth – resources become less available, growth slows or stops
S-shape curve
Carrying Capacity – the number an environment can support

10. Limits to Growth
Density-Dependent Factors –depends on population size
competition
predation
parasitism and disease

11. Density-Independent Factors – does not depend on population size
Unusual weather
Natural disasters
Some human activities